Neck sparing total hip implant methods

ABSTRACT

A femoral prosthesis. The femoral prosthesis includes an implant body having a proximal end and a distal end and a shoulder at the proximal end, the shoulder being structured and dimensioned for a tight press fit into the neck of a femur. The implant body includes a trunk at the distal end, the trunk having a wedge formed by a tapered portion extending in the direction of the distal end of the implant body. The implant body also includes a medial column extending from the shoulder toward the distal end and a lateral column extending from the shoulder toward the distal end. The wedge, the medial column, and the lateral column to provide multi-planar stability for the implant body and surface area for fixation of the implant body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.12/874,132, filed Sep. 1, 2010, which claims the benefit of U.S.Provisional Application No. 61/238,898, filed Sep. 1, 2009, entitledFEMORAL PROSTHESIS, which are both hereby incorporated by this referenceherein in their entireties, including but not limited to those portionsthat specifically appear hereinafter, the incorporation by referencebeing made with the following exception: In the event that any portionof the above-referenced provisional applications is inconsistent withthis application, this application supercedes said portion of saidabove-referenced provisional applications.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND

1. The Field of the Present Disclosure.

The present disclosure relates generally to an orthopedic implant foruse in a total hip arthroplasty, i.e., a total hip replacement. Morespecifically, the disclosure relates to a femoral component of a totalhip implant, and more particularly, but not necessarily entirely, to afemoral neck sparing implant that may be placed or located in a proximalfemur.

2. Description of Related Art

This invention relates in general to prosthesis, parts thereof, or aidsand accessories therefor. More particularly, the invention relates to afemoral prosthesis.

Total hip replacement has become the standard of care treatment toaddress a variety of degenerative and traumatic processes of the hipjoint.

Much has been learned and developed over the last several decades ofpractice and research. Previously, much bone resection and marrowexcavation has been necessary to accomplish implant longevity andstability. As time has proceeded, more tissue and bone sparing surgicaltechniques have been developed. These techniques in general are tofacilitate less bone loss in future revision surgeries and to decreasesoft tissue injury. Bone is lost from both stress shielding andosteolysis. The problem of bone loss from osteolysis has largely beensolved by improvement in the wear properties of modern bearing surfaces.Stress shielding bone loss has been improved by loading the proximalfemur with tapered stem geometries or surface replacement devices.Surface replacement devices have a multitude of limitations. First, theprocedure can require relatively large exposure and therefore can hardlybe called tissue sparing, although bone sparing. Second, the compromisedbone of the femoral head is often a poor foundation and can cause earlyor late failure from collapse. Lastly, femoral neck fracture can occur.

Previous devices have relied on entry into the femoral canal either in astraight entry or in a curvilinear fashion. Some have considered theproximal femoral metaphyseal bone incapable of sustaining load.

Modern minimally invasive surgery, in particular, the “anterior supinemuscle sparing” approach, is made more difficult by the straightdiaphyseal engaging stems. Shorter curved tapered stems have been madewith some improvement in the ease of implantation. However, femoralinsertion can still be very challenging.

The prior art is thus characterized by several disadvantages that areaddressed by the present disclosure. The present disclosure minimizes,and in some aspects eliminates, the above-mentioned failures, and otherproblems, by utilizing the methods and structural features describedherein.

The features and advantages of the present disclosure will be set forthin the description which follows, and in part will be apparent from thedescription, or may be learned by the practice of the present disclosurewithout undue experimentation. The features and advantages of thepresent disclosure may be realized and obtained by means of theinstruments and combinations particularly pointed out in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the disclosure will become apparent froma consideration of the subsequent detailed description presented inconnection with the accompanying drawings in which:

FIG. 1 is a partial sectional view in elevation of the proximal end of afemur and a femoral prosthesis.

FIG. 2A is a diagrammatic partial plan view of the femur and prosthesisshown in FIG. 1, showing hoop stress at the femoral neck.

FIGS. 2B-2C are diagrammatic partial plan views of other femurs and theprosthesis, showing hoop stress at the femoral necks.

FIG. 3 is an enlarged perspective view of a femoral prosthesis.

FIG. 4 is an end view of the femoral prosthesis shown in FIG. 3.

FIG. 5 is an enlarged perspective view of another femoral prosthesis.

FIG. 6 is an end view of the femoral prosthesis shown in FIG. 5.

FIG. 7 is an exploded sectional view of the prosthesis shown in FIG. 5.

FIGS. 8A-8B are sectional views of prosthesis.

FIG. 9A shows a perspective view of a femoral prosthesis.

FIG. 9B shows an anterior view of the femoral prosthesis of FIG. 9A.

FIG. 9C shows lateral view of the femoral prosthesis of FIG. 9A.

FIG. 10A shows a perspective view of a femoral prosthesis.

FIG. 10B shows an anterior view of the femoral prosthesis of FIG. 10A.

FIG. 10C shows lateral view of the femoral prosthesis of FIG. 10A.

FIG. 11A shows a perspective view of a femoral prosthesis.

FIG. 11B shows an anterior view of the femoral prosthesis of FIG. 11A.

FIG. 11C shows lateral view of the femoral prosthesis of FIG. 11A.

FIG. 12 illustrates an embodiment of a hip prosthesis having a pluralityof surface treatments.

FIG. 13 depicts a lateral cross-sectional view of one embodiment of animplant body for a hip prosthesis.

FIG. 14 depicts a lateral cross-sectional view of another embodiment ofan implant body for a hip prosthesis.

FIG. 15 is a perspective view illustrating one embodiment of a femoralprosthesis.

FIG. 16 is a perspective view illustrating another embodiment of afemoral prosthesis.

FIGS. 17A-17F illustrate one embodiment of a system and method forinstalling a hip implant body into a femur.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles inaccordance with the disclosure, reference will now be made to theembodiments illustrated in the drawings and specific language will beused to describe the same. It will nevertheless be understood that nolimitation of the scope of the disclosure is thereby intended. Anyalterations and further modifications of the inventive featuresillustrated herein, and any additional applications of the principles ofthe disclosure as illustrated herein, which would normally occur to oneskilled in the relevant art and having possession of this disclosure,are to be considered within the scope of the disclosure claimed.

It is to be understood that this disclosure is not limited to theparticular configurations, process steps, and materials disclosed hereinas such configurations, process steps, and materials may vary somewhat.It is also to be understood that the terminology employed herein is usedfor the purpose of describing particular embodiments only and is notintended to be limiting since the scope of the present disclosure willbe limited only by the appended claims and equivalents thereof.

Any publications and other reference materials referred to herein todescribe the background of the disclosure, and to provide additionaldetail regarding its practice, are hereby incorporated by referenceherein in their entireties, with the following exception: In the eventthat any portion of said reference materials is inconsistent with thisapplication, this application supercedes said reference materials.Reference materials discussed herein are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as a suggestion or admission that theinventors are not entitled to antedate such disclosure by virtue ofprior disclosure, or to distinguish the present disclosure from thesubject matter disclosed in the reference materials.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise.

In describing and claiming the present disclosure, the followingterminology will be used in accordance with the definitions set outbelow.

As used herein, the terms “comprising,” “including,” “containing,”“characterized by,” and grammatical equivalents thereof are inclusive oropen-ended terms that do not exclude additional, unrecited elements ormethod steps.

As used herein, the term “proximal” is a relative term and shall referbroadly to the concept of a more near portion. For example, the neck isthe proximal-most portion of the prosthesis, relative to other portionsof the prosthesis, because it is the nearest portion when saidprosthesis is installed. When referring to a portion of the human bodyor a device or structure attached to the human body, the term “proximal”is a relative term and shall refer broadly to the concept of a portioncloser to the center of the body.

As used herein, the term “distal” shall generally refer to the oppositeof proximal, and thus to the concept of a further portion, a furthestportion, or a portion more distant from the center of the body,depending upon the context.

As used herein, the phrase “in an at least partially proximal-to-distaldirection” shall refer generally to a two-dimensional concept ofdirection in which the “proximal-to-distal” direction defines onedirection or dimension. An item that extends in a non-parallel directionwith respect to the “proximal-to-distal” direction, that is, at anon-straight angle thereto, thereby involves two components ofdirection, one of which is in the “proximal-to-distal” direction and theother being in a direction orthogonal to the “proximal-to-distal”direction. For example, the medial column extends in aproximal-to-distal direction.

It will be appreciated that the structure and apparatus disclosed hereinis merely one example of a means for a femoral prosthesis, and it shouldbe appreciated that any structure, apparatus or system for femoralprosthesis which performs functions the same as, or equivalent to, thosedisclosed herein are intended to fall within the scope of a means for afemoral prosthesis, including those structures, apparatus or systems fora femoral prosthesis which are presently known, or which may becomeavailable in the future. Anything which functions the same as, orequivalently to, a means for a femoral prosthesis falls within the scopeof this element.

Referring now to the drawings, there is illustrated in the FIGS. 1-4 oneembodiment of a femoral prosthesis 10 generally comprising an implantbody 12 supporting a neck 14, which may be without modularity oroptionally a modular neck. The neck 14 may have a Morse taper, as isknown in the art, to accommodate a substantially spherical joint ball,bearing or prosthetic head 16 at the proximal end of the neck 14. Thedesign may accommodate a wide variety of spherical ball sizes and/ormaterials (e.g., metal or ceramic).

Close below this prosthetic head 16, the implant body 12 may be providedwith a shoulder 18 at its proximal end. This shoulder 18 may be conicalor tapered at an angle. The angle may be in a range between about 2degrees and about 10 degrees, or some other suitable angle that createsa Morse tapered or other machine taper retentive effect in the neck ofthe femur 26, as will become apparent in the description that follows.The shoulder 18 may be structured and dimensioned for a tight press fitinto the femoral neck 30, and thus increase hoop stress at the neck 30(i.e., depicted by the radially directed arrows in FIGS. 2A-2C). Theshoulder 18 may have a fixation surface, which may be rough and porousto promote impaction and/or press-fit of the shoulder 18 into thefemoral neck 30 and subsequent fixation (e.g., ingrowth or ongrowth) ofthe cortical bone of the femoral neck 30 into shoulder 18.

As shown in FIG. 3, FIGS. 5-7 include a trunk 20. The trunk 20 of theembodiment shown in FIGS. 5-7 includes an alternative arrangement of thefins 22, as shown.

Immediately below the shoulder 18, the implant body 12 merges into atrunk 20. The trunk 20 may have a generally sharply tapered portionextending from the shoulder 18 in the direction of the distal end of thetrunk 20 to form a wedge 21, as shown for example in FIG. 8A, or a knifeedge, as shown for example in FIG. 8B. The trunk 20 may be provided withlongitudinally extending webs or fins 22. The fins 22 may function toprovide a large surface area for initial multi-planar stability and anincreased surface area for long term fixation (e.g., bony ingrowth orongrowth), as will become apparent in the description that follows.Although other fin configurations may be suitable, the illustratedimplant body 12 has one or more superior (i.e., higher) fins and one ormore inferior (i.e., lower) fins. One or more central fins may also beprovided. The fins 22 may provide increased surface area contact ormaximize surface area contact in the metaphyseal bone for fixation(e.g., bony ingrowth or ongrowth) and initial or preliminary cancellousbone press fit stability or fixation. The implant body 12 (e.g., theshoulder 18 and trunk 20) may be porous to provide long term stabilityfrom bony ingrowth or ongrowth. The wedge 21 of the trunk 21 mayfacilitate dilation and impaction of the cancellous bone. This mayprevent the need for removal of substantial cancellous bone.

The shoulder 18 may be shaped and dimensioned to approximate the shapeand dimension of the femoral neck to further maximize surface areacontact. The implant body 12 may have an overall elongated lateralcross-section, or a cross-section that otherwise fits the anatomy of thefemoral neck to reduce rotation, and may have a substantially straightlong axis so the implant body 12 does not curve into the diaphysis ofthe femur. To this end, the superior and inferior fins 22 may be curvedto approximate the geometry of the superior and inferior part of theneck 18 (see FIGS. 2A-2C). These curves may be substantially the samegeometry as the corresponding curved portions of the femoral neck. Theimplant body 12 and neck 14 may be metal. The metal used may betitanium, chrome-cobalt or stainless steel based, or any metal commonlyused in hip prosthesis construction.

The implant body 12 may be porous, and may have a porous coating, layeror surface 24. An example of such a coating is titanium plasma spray,which promotes bony ingrowth or ongrowth into prosthetic implants. Thecoating may further be in the form of sintered beads, plasma spray, ahydroxyapatite (HA), trabecular metal, porous titanium, or anothersuitable form, depending on the type of metal used for the prosthesis10, as the prosthesis may be entirely formed from the same material(e.g., titanium, all chrome cobalt, or other suitable material).

It should be appreciated that the implant body 12 of the prosthesis 10may be available in various sizes depending on anatomical requirements,and as mentioned above, the prosthetic head 16 may be a modular head, ora non-modular head.

Fixation of the prosthesis 10 to the femur can be achieved by insertingthe implant body 12 into the open neck of a femur, along the anatomic orlongitudinal axis of the femoral neck, as set forth for example in thedescription that follows. Because the implant body 12 is straight andoriented along the longitudinal axis of the femoral neck 30, rotationalalignment can be allowed to shift based on anatomical variations.

In FIG. 1, there is illustrated femur 26 with an osteotomy or cutextending along a plane 28 perpendicular to the longitudinal axis of thefemoral neck 30.

The implant body 12 may be fitted into the femoral neck 30 at an angle βto the longitudinal axis 36 of the femur 26 so that the long axis 38 ofthe implant body 12 corresponds approximately to the axis of a healthyfemoral neck. That is to say, the implant body 12 may be inserted fromthe proximal direction into the femoral neck 30 so that the long axis 38of the implant body 12 coincides with the axis made in the preoperativefemur by an imaginary line connecting the center of the femoral neck 30with the center of the femoral head, or at an angle β approximatelycorresponding to the normal anatomy of the patient (usually between 120and 150 degrees), and preferably the cervico-diaphyseal angle (i.e., theangle between the long axis of the femoral neck and the longitudinalaxis 36 of the femur 26), which varies per individual.

In some embodiments, the implant body 12 may contact the inner corticallateral wall 40 of the femoral neck 30 by tightly fitting the implantbody 12 into the femoral neck 30. In another embodiment, the implantbody 12 does not contact the inner cortical lateral wall 40. The implantbody 12 may have an overall length 102. The implant body 12 may be sizedsuch that the overall length 102 causes the distal end of the implantbody 12 to extend between sixty (60) percent and eighty (80) percent ofa distance 104 from a resection of the femoral neck 28 to the innercortical lateral wall 40.

The tapered shoulder 18 at the proximal end of the implant body 12, wheninserted in the neck 30 of the femur 26, may form a tight press fitwithin the neck 30 of the femur 26 to provide optimum contact and loadtransfer between the engagement surfaces of the shoulder 18 of theimplant body 12 and the neck 30 of the femur 26. The tight press fitconfiguration may increase the hoop stress at the neck 30 of the femur26 (as represented by the arrows in FIGS. 2A-2C), and thus increase theretentive effect of the shoulder 18 in the neck 30 of the femur 26. Itshould be appreciated that the shape of the implant body 12 may differfrom that of the femoral neck 30 (e.g., due to anatomic variations). Theimplant body 12 may simply wedge into the “hoop” formed by the femoralneck 30 and thus increase hoop stress. It should be appreciated that theshape of the implant body 12 could be custom made to each patient, forexample, using magnetic resonance imaging (MRI) or computer tomography(CT) templating, as mentioned below.

The surfaces of the implant body 12 disposed for engaging the interiorof the femur 26 are broadly fixation surfaces. The wedge 21 and thelongitudinally extending fins 22 of the trunk 20 of the implant body 12may penetrate the spongiosa 41 inside the femur 26 to secure the implantbody 12 in the femur 26. The overall elongated shape of the lateralcross-section of the implant body 12 may hold the implant body 12securely against movement about the long axis 38 of the implant body 12after implantation. The wedge 21 and the fins 22 may provide increasedsurface contact for initial and late fixation. Fixation (e.g., bonyingrowth or ongrowth) may be encouraged on all surfaces of the implantbody 12, including shoulder 18, the wedge 21, and the fins 22. It shouldbe appreciated that the shape and highly porous surface of the implantbody 12, including the shoulder 18, the wedge 21, and the fins 22, may,in addition to resisting rotational movement, resist movement in allplanes.

The distal end of the implant body 12 may be cut on an angle to the longaxis 38 of the implant body 12, so that the distal end is substantiallypointed. Moreover, the distal end of the implant body 12, when insertedin the femur 26, may be generally aligned with or parallel to the innersurface of the lateral wall 42 of the femur 26 or along the longitudinalaxis 38 of the femur 26. The distal end of the implant body 12 remainswithin the femur 26, so as to not extend beyond the femur 26. It shouldbe appreciated that the distal end of the implant body 12 may be curved.For example, a curved surface may be superimposed on the angled distalend of the implant body 12, or otherwise curved, such as curvedtransversely in relation to the long axis 38 of the implant body, toprovide clearance between the distal end of the implant body 12 and theinner surface of the lateral wall 42 of the femur 26, as clearly shownin FIG. 1.

It should be appreciated that the prosthesis 10 may be installed andused without requiring any other fastener on the femur 26. Theprosthesis does not require screws or other fasteners to be placed inthe femur 26, and it does not require any sort of support plate on thelateral wall of the femur 26.

Notwithstanding, one or more optional fasteners 43, such as pins, spikesor screws, may attach the implant body 12 to the lateral wall 42 of thefemur 26, or just contact the inner surface of the lateral wall 42(without penetration), which may add initial stability to the implantbody 12. The fasteners 43 may add stability to the construct by givingfurther stability to the implant body 12 of the prosthesis 10.

A fastener 43, for example, may pass through a tubular channel 46 in thecenter of the implant body 12 of the prosthesis 10. The head of thecenter fastener 43 may be located in the base of a female Morse taper 45or other machine taper in the implant body 12, if a modular neck isused. Additionally, fasteners 43 may also pass through tubular channels46 in the implant body 12 of the prosthesis 10, flanking the center ofthe implant body 12, adjacent the superior and inferior fins. Theflanking fasteners can be used to the exclusion of the center fastenersand vice versa. For example, if a non-modular neck is used, flankingfasteners may be used to the exclusion of the center fasteners. Itshould be appreciated that the fasteners 43 may or may not penetrate thelateral wall 42 of the femur 10 to breach the lateral wall 42. Thefasteners 43 may function to further reduce the likelihood of movementof the prosthesis 10 in all planes within the femoral neck 30. The useof fasteners 43 may be dependent on the bone quality of the patient.

One or more anterior/posterior fasteners 44, such as screws (best shownin FIG. 3) may be provided. These fasteners 44 pass through one or moreanterior/posterior cylindrical channels 106 in the implant body 12, andpast though and/or threadably engage the anterior/posterior cortex ofthe femur 26. The fasteners 44 may allow for some load transfer to theanterior and posterior cortex of the femur 26 through the fasteners 44.In the illustrated embodiment, the one or more anterior/posteriorchannels 106 are circular in cross section. In certain embodiments, theone or more anterior/posterior channels 106 may be elongate in crosssection. It should be appreciated that the prosthesis 10 can be usedwithout cement.

If a modular neck 14 is used, the distal end of the neck 14 may have amale Morse taper 48 or other machine taper that may cooperate with afemale Morse taper 45 or other machine taper in the implant body 12 andthus act as a joining portion in connecting the implant body 12 of theprosthesis 10 for the prosthetic head 16. Adjustments in the length ofthe neck 14 may be accommodated with the provision of necks of varyinglength. The Morse tapers 46, 48 or other machine tapers may be providedto accommodate a modular neck 14. Such tapers would not be necessary ifa non-modular neck is used.

The prosthetic head 16 may engage a male Morse taper 50 or other machinetaper provided at the proximal end of the neck 14. The prosthetic head16 may have a female Morse taper 52 or other machine taper configured toreceive the male Morse tapered or other machine tapered conical head 50at the proximal end of the neck 14, as is well known in the art. Hence,a modular neck 14 may have a Morse taper 48, 50 or other machine taperat each end, and a length of straight section connecting the Morsetapers 48, 50 or other machine tapers. The length of the straightsection may vary so that necks of various sizes can be used for patientswith differing requirements.

Prosthetic heads may be of various diameters depending on the type ofhip arthroplasty (i.e., hip replacement) being performed (e.g.,hemiarthoplasy versus total hip arthroplasty), and the type ofacetabular component used.

The prosthesis 10 loads the proximal end of the femur 26, and thusprevents bone resorption. Very little bone is resected in theimplantation process. Hence, the femoral prosthesis 10 is bone sparing.The prosthesis 10 may maintain its stability on initial implantationwith the press fit in the femoral neck 30 via high hoop stress and alarge metaphyseal bone surface contact area. This prosthesis may providelong term reliability while simplifying the technique of implantationthrough an anterior approach. The prosthesis permits ease of insertionvia the anterior approach, following the anatomic neck angle. Thisallows less tissue dissection because there is less need to elevate thefemur in order to gain access to the longitudinal axis of the femoraldiaphysis.

The prosthesis 10 is ideal for MRI or CT templating in the hip. UsingMRI or CT templating, a custom prosthesis as described above may beproduced to specifically approximate or match an individual patient'sanatomy, thus producing a custom-fit implant body.

FIGS. 9A-9C illustrate an alternative embodiment of a femoral prosthesis900. FIG. 9A shows a perspective view of the femoral prosthesis 900.FIG. 9B shows an anterior view of the femoral prosthesis 900. FIG. 9Cshows lateral view of the femoral prosthesis 900. The femoral prosthesis900 includes a neck 902 and an implant body 904. The implant body 904includes a proximal end 906 and a distal end 908, a shoulder 910 and atrunk 912. The shoulder 910, in some embodiments, located at or near theproximal end 906 of the implant body 904 and is similar to the shoulder18 described in relation to FIGS. 1-4. The shoulder 910 may constitutean outer perimeter of the implant body 904. The femoral prosthesis 900is used in a hip replacement.

The trunk 912, in one embodiment, extends from the shoulder 910 towardthe distal end 906 of the implant body 904. The trunk 912 includesmedial column 914, a lateral column 916, and a connecting body 918 thatseparates the medial column 914 and the lateral column 916. Theconnecting body 918 may be connected to the medial column 914 on amedial side of the connecting body 918, and connected to the lateralcolumn 916 on a lateral side of the connecting body 918.

In some embodiments, the connecting body 918 is a wedge and has a crosssection that is substantially wedge-shaped. For example, the connectingbody may have a cross section similar to that illustrated in FIG. 8A.The connecting body 918 may have a cross section that has a knife edgeshape, similar to that illustrated in FIG. 8B.

As best shown in FIG. 9B the implant body 904 has a long axis 920running through the center of the neck 902 and the length of the implantbody 904. The implant body 904, in some embodiments, is substantiallystraight, and the long axis 920 is substantially straight and in thecenter of the implant body 904.

The implant body 904 may include a medial column axis 922. The medialcolumn axis 922 runs essentially through the center of the medial column914. The medial column axis 922 may run through successive center pointsof the medial column 914. In one embodiment, the medial column 914 has acurved outer surface (best seen in FIG. 13) with a radius and a centerpoint. In some embodiments, the medial column axis 922 runs through thecenter points. In one embodiment, the medial column axis 922 issubstantially parallel to the long axis 920.

The implant body 904 may include a lateral column axis 924. The lateralcolumn axis 924 runs essentially through the center of the lateralcolumn 916. The lateral column axis 924 may run through successivecenter points of the lateral column 916. In one embodiment, the lateralcolumn 916 has a curved outer surface (best seen in FIG. 13) with aradius and a center point. In some embodiments, the lateral column axis924 runs through the center points. In one embodiment, the lateralcolumn axis 924 is substantially parallel to the long axis 920. In someembodiments, the medial column axis 922 and the lateral column axis 924are substantially parallel.

The implant body 904, in some embodiments, includes a flare 926 on amedial side of the shoulder 910 and a proximal portion of the medialcolumn 914. The flare 926 extends radially from the medial column axis922, becoming larger as the flare 926 progresses along the implant body904 in a distal to proximal direction. The flare 926 acts to load thecalcar region of the resected femur and helps prevent bone resorbtion.

In certain embodiments, the implant body 904 includes one or moreterraces 928 on the connecting body 918. The terraces 928 may bearranged such that each terrace 928 undercuts a more proximal level ofthe connecting body 918. In some embodiments, the connecting body 918 isroughly wedge-shaped, and the slope of the wedge is formed by successiveterraces 928 on the anterior and posterior faces of the connecting body918. The terraces 928 may provide increased boding and stress offloadingof the implant body 904 to the femur.

In some embodiments, the terraces 928 are angled relative to the longaxis 920 of the implant body 904 at a terrace angle 930. In certainembodiments, the terrace angle 930 is between 125 degrees and 160degrees. In one embodiment, the terrace angle 930 is such that theterraces 928 run perpendicular to a long axis of the femur when theimplant body 904 is installed in the femur. In an alternate embodiment,the terrace angle 930 is such that the terraces 928 run perpendicular tothe long axis 920 of the implant body 904.

The distal end 908 of the implant body 904, in some embodiments, isangled relative to the long axis 920 of the implant body 904. In oneembodiment, the distal end 908 is angled such that it is roughlyparallel with the inner cortical wall of the femur when the implant body904 is installed. In some embodiments, the distal end 908 has a curvedsurface 932 superimposed on the distal end 908. In one embodiment, thecurved surface 932 is a transverse curve.

The implant body 904, in some embodiments, includes a medial cannula934. The medial cannula 934 may run the length of the implant body 904such that it is accessible at both the proximal end 906 and the distalend 908 of the implant body 904. In one embodiment, the medial cannula934 runs along the medial column axis 922. The medial cannula 934provides a pathway for a guide wire to guide the implant body 904 duringinstallation.

In some embodiments, the implant body 904 includes a lateral cannula936. The lateral cannula 936 may run the length of the implant body 904such that it is accessible at both the proximal end 906 and the distalend 908 of the implant body 904. In one embodiment, the lateral cannula936 runs along the lateral column axis 924. The lateral cannula 936provides a pathway for a guide wire to guide the implant body 904 duringinstallation.

The medial column 914, in one embodiment, has an inside surface 938. Theinside surface 938 may be formed by a taper of the connecting body 918relative to the medial column 914. In one embodiment, the inside surface938 is substantially flat, or planar. In an alternate embodiment, theinside surface 938 is convex over at least a portion of the insidesurface 938. The lateral column 916 may have a corresponding insidesurface (not shown) which may also be substantially planar, convex, oranother shape over at least a portion of the inside surface of thelateral column 916.

In one embodiment, the medial column 914 and the lateral column 916 havea substantially constant lateral cross sectional area along the trunk912. In some embodiments, the medial column 914 has a decreasing crosssectional area in the region where the flare 926 is located as crosssections move from the proximal end 906 toward the distal end 908 of theimplant body 904.

FIGS. 10A-10C illustrate another embodiment of a femoral prosthesis1000. FIG. 10A shows a perspective view of the femoral prosthesis 1000.FIG. 10B shows an anterior view of the femoral prosthesis 1000. FIG. 10Cshows lateral view of the femoral prosthesis 1000. The femoralprosthesis 1000 includes many structures and features similar to thoseof the femoral prosthesis 900 described above. The femoral prosthesis1000 is used in a hip replacement.

In one embodiment, the femoral prosthesis 1000 includes an implant body1002 with a proximal end 1004, a distal end 1006, a medial column 1008,and a lateral column 1010. The medial column 1008, in one embodiment,tapers along at least a portion of the medial column 1008 from theproximal end 1004 to the distal end 1006. In one embodiment, the crosssectional area of the medial column 1008 decreases along at least aportion of the column as cross sections are viewed in a proximal todistal direction.

The lateral column 1010, in one embodiment, tapers along at least aportion of the lateral column 1010 from the proximal end 1004 to thedistal end 1006. In one embodiment, the cross sectional area of thelateral column 1010 decreases along at least a portion of the column ascross sections are viewed in a proximal to distal direction.

In some embodiments, the implant body 1002 includes a long axis 1012running through the center of the implant body 1002 along its length.The implant body 1002, in some embodiments, is substantially straight,and the long axis 1012 is substantially straight and in the center ofthe implant body 1002.

The implant body 1002 may include a medial column axis 1014. The medialcolumn axis 1014 runs essentially through the center of the medialcolumn 1008. The medial column axis 1014 may run through successivecenter points of the medial column 1008. In one embodiment, the medialcolumn 1008 has a curved outer surface (best seen in FIG. 13) with aradius and a center point. In some embodiments, the medial column axis1014 runs through the center points. In one embodiment, the medialcolumn axis 1014 is substantially parallel to the long axis 1012.

The implant body 1002 may include a lateral column axis 1016. Thelateral column axis 1016 runs essentially through the center of thelateral column 1010. The lateral column axis 1016 may run throughsuccessive center points of the lateral column 1010. In one embodiment,the lateral column 1010 has a curved outer surface (best seen in FIG.13) with a radius and a center point. In some embodiments, the lateralcolumn axis 1016 runs through the center points. In one embodiment, thelateral column axis 1016 is substantially parallel to the long axis1012. In some embodiments, the medial column axis 1014 and the lateralcolumn axis 1016 are substantially parallel.

The implant body 1002, in some embodiments, includes a medial cannula1018. The medial cannula 1018 may run the length of the implant body1002 such that it is accessible at both the proximal end 1004 and thedistal end 1006 of the implant body 1002. In one embodiment, the medialcannula 1018 runs along the medial column axis 1014. The medial cannula1018 provides a pathway for a guide wire to guide the implant body 1002during installation.

In some embodiments, the implant body 1002 includes a lateral cannula1020. The lateral cannula 1020 may run the length of the implant body1002 such that it is accessible at both the proximal end 1004 and thedistal end 1006 of the implant body 1002. In one embodiment, the lateralcannula 1020 runs along the lateral column axis 1016. The lateralcannula 1020 provides a pathway for a guide wire to guide the implantbody 1002 during installation.

FIGS. 11A-11C illustrate another embodiment of a femoral prosthesis1100. FIG. 11A shows a perspective view of the femoral prosthesis 1100.FIG. 11B shows an anterior view of the femoral prosthesis 1100. FIG. 11Cshows lateral view of the femoral prosthesis 1100. The femoralprosthesis 1100 includes many structures and features similar to thoseof the femoral prosthesis 900 described above. The femoral prosthesis1100 is used in a hip replacement.

In one embodiment, the femoral prosthesis 1100 includes an implant body1102 with a proximal end 1104, a distal end 1106, a medial column 1108,and a lateral column 1110.

In some embodiments, the implant body 1102 includes a long axis 1112running through the center of the implant body 1102 along its length.The implant body 1102, in some embodiments, is substantially straight,and the long axis 1112 is substantially straight and in the center ofthe implant body 1102.

The implant body 1102 may include a medial column axis 1114. The medialcolumn axis 1114 runs essentially through the center of the medialcolumn 1108. The medial column axis 1114 may run through successivecenter points of the medial column 1108. In one embodiment, the medialcolumn 1108 has a curved outer surface (best seen in FIG. 13) with aradius and a center point. In some embodiments, the medial column axis1114 runs through the center points. In one embodiment, the medialcolumn axis 1114 is substantially parallel to the long axis 1112.

The implant body 1102 may include a lateral column axis 1116. Thelateral column axis 1116 runs essentially through the center of thelateral column 1110. The lateral column axis 1116 may run throughsuccessive center points of the lateral column 1110. In one embodiment,the lateral column 1110 has a curved outer surface (best seen in FIG.13) with a radius and a center point. In some embodiments, the lateralcolumn axis 1116 runs through the center points. In one embodiment, thelateral column axis 1116 is substantially parallel to the long axis1112. In some embodiments, the medial column axis 1114 and the lateralcolumn axis 1116 are substantially parallel.

The implant body 1102, in some embodiments, includes a medial cannula1118. The medial cannula 1118 may run the length of the implant body1102 such that it is accessible at both the proximal end 1104 and thedistal end 1106 of the implant body 1102. In one embodiment, the medialcannula 1118 runs along the medial column axis 1114. The medial cannula1118 provides a pathway for a guide wire to guide the implant body 1102during installation.

In some embodiments, the implant body 1102 includes a lateral cannula1120. The lateral cannula 1120 may run the length of the implant body1102 such that it is accessible at both the proximal end 1104 and thedistal end 1106 of the implant body 1102. In one embodiment, the lateralcannula 1120 runs along the lateral column axis 1116. The lateralcannula 1120 provides a pathway for a guide wire to guide the implantbody 1102 during installation.

The medial column 1108, in one embodiment, has an inside surface 1122.The inside surface 1122 may be formed by a taper of the connecting bodyrelative to the medial column 1108. In one embodiment, the insidesurface 1122 is substantially concave over at least a portion of theinside surface 1122. The lateral column 1110 may have a correspondinginside surface (not shown) which may also be substantially concave overat least a portion of the inside surface of the lateral column 1110.

FIG. 12 illustrates an embodiment of a hip prosthesis 1200 having aplurality of surface treatments. The hip prosthesis includes an implantbody 1202 having a proximal region 1204, an intermediate region 1206,and a distal region 1208.

In some embodiments, the proximal region 1204 has a first surfacetreatment 1210 that is relatively porous. The relatively high porosityof the first surface treatment 1210 encourages bone ingrowth and acts tosecure the proximal region 1204 of the implant body 1202 to the bonewhen the implant body 1202 is installed.

The intermediate region 1206, in one embodiment, has a second surfacetreatment 1212 that has an intermediate porosity. The intermediateporosity of the second surface treatment 1212 encourages some boneingrowth, but less than that of the first surface treatment 1210.Consequently, bone ingrowth over the intermediate region 1206 securesthe implant body 1202 to a degree, but less so than the proximal region1204. The somewhat reduced fixation over the intermediate region 1206may facilitate retrieval of the implant body 1202.

In one embodiment, the distal region 1208 has a third surface treatment1214 having a low porosity. The low porosity of the third surfacetreatment 1214 resists bone ingrowth, resulting in relatively weakerfixation of the distal region 1208 to the femur. The weaker fixation ofthe distal region 1208 may facilitate retrieval of the implant body1202.

In some embodiments, boundaries between the first surface treatment1210, the second surface treatment 1212, and the third surface treatment1214 are well defined. The boundaries may be angled relative to a longaxis of the implant body 1202, or they may be perpendicular to the longaxis of the implant body 1202. In one embodiment, the boundaries areangled such that they proceed in a lateral and distal direction, asshown in FIG. 12. In an alternate embodiment, the boundaries are angledsuch that they proceed in a medial and distal direction.

FIG. 13 depicts a lateral cross-sectional view of one embodiment of animplant body for a hip prosthesis. The lateral cross-sectional view istaken along a plane perpendicular to a long axis of the implant body.The cross-sectional view shows a lateral column 1302, a medial column1304, and a connecting body 1306.

The lateral column 1302, in one embodiment, includes a lateral outersurface 1308 that defines a portion of a perimeter of the implant body.The cross section of the lateral outer surface 1308 is substantially atleast a portion of a circle, or an arc. In certain embodiments, thecross section of the lateral outer surface 1308 of the lateral column1302 includes an arc having a constant radius 1310. In one embodiment,the lateral outer surface 1308 is a semicircle.

The medial column 1304, in one embodiment, includes a medial outersurface 1312 that defines a portion of a perimeter of the implant body.The cross section of the medial outer surface 1310 is substantially atleast a portion of a circle, or an arc. In certain embodiments, thecross section of the medial outer surface 1312 of the medial column 1304includes an arc having a constant radius 1314. In one embodiment, themedial outer surface 1312 is a semicircle.

In one embodiment, the radius 1310 of the lateral outer surface 1308 andthe radius 1314 of the medial outer surface 1312 are substantiallyequal. In one embodiment, the cross-sectional area of the medial column1304 is substantially equal to the cross-sectional area of the lateralcolumn 1302.

The lateral column 1302, in some embodiments, includes a lateral cannula1316 at the center point of the arc defining the lateral outer surface1308. In one embodiment, the medial column 1304 includes a medialcannula 1318 at the center point of the arc defining the medial outersurface 1312.

In certain embodiments, the connecting body 1306 includes an anteriorwall 1320 and a posterior wall 1322. The cross section of the anteriorwall 1320 and the posterior wall 1322 are parallel in one embodiment.

FIG. 14 depicts a lateral cross-sectional view of one embodiment of animplant body for a hip prosthesis. The lateral cross-sectional view istaken along a plane perpendicular to a long axis of the implant body.The cross-sectional view shows a lateral column 1402, a medial column1404, and a connecting body 1406.

The lateral column 1402, in one embodiment, includes a lateral outersurface 1408 that defines a portion of a perimeter of the implant body.The cross section of the lateral outer surface 1408 is substantially atleast a portion of a circle, or an arc. In certain embodiments, thecross section of the lateral outer surface 1408 of the lateral column1402 includes an arc having a constant radius 1410. In one embodiment,the lateral outer surface 1408 is a semicircle.

The medial column 1404, in one embodiment, includes a medial outersurface 1412 that defines a portion of a perimeter of the implant body.The cross section of the medial outer surface 1410 is substantially atleast a portion of a circle, or an arc. In certain embodiments, thecross section of the medial outer surface 1412 of the medial column 1404includes an arc having a constant radius 1414. In one embodiment, themedial outer surface 1412 is a semicircle.

In one embodiment, the radius 1410 of the lateral outer surface 1408 andthe radius 1414 of the medial outer surface 1412 are substantiallydifferent. For example, the radius 1414 of the medial outer surface 1412may be larger than the radius 1410 of the lateral outer surface 1408. Inone embodiment, the cross-sectional area of the medial column 1404 isthirty (30) percent larger than the cross-sectional area of the lateralcolumn 1402.

In certain embodiments, the connecting body 1406 includes an anteriorwall 1420 and a posterior wall 1422. The cross section of the anteriorwall 1420 and the posterior wall 1422 are angled relative to one anotherin one embodiment.

The lateral column 1402, in some embodiments, includes a lateral cannula1416 at the center point of the arc defining the lateral outer surface1408. In one embodiment, the medial column 1404 includes a medialcannula 1418 at the center point of the arc defining the medial outersurface 1412.

FIG. 15 is a perspective view illustrating one embodiment of a femoralprosthesis 1500. The femoral prosthesis includes an implant body 1502.The femoral prosthesis 1500 is used in hip replacement.

The implant body 1502, in one embodiment, includes a proximal end 1504with a collar 1506 disposed at or near the proximal end 1504. The collar1506 may be a portion of the implant body 1502 that extends radially asthe proximal end 1504 of the implant body 1502 is approached along theimplant body 1502. The collar 1506 may serve to limit the extent towhich the implant body 1502 may be inserted into the femur. Asillustrated in FIG. 15, the implant body 1502 may include a collar 1506.In an alternate embodiment, the implant body 1502 may be collarless.

FIG. 16 is a perspective view illustrating one embodiment of a femoralprosthesis 1600. The femoral prosthesis includes an implant body 1602.The femoral prosthesis 1600 is used in hip replacement.

The implant body 1602, in one embodiment, includes a proximal end 1604with a stepped shoulder 1606 disposed at or near the proximal end 1604.The stepped shoulder 1606 may be a portion of the implant body 1602 thatincludes one or more steps. The stepped shoulder 1606 may serve toimprove bone ingrowth and fixation of the implant body 1602 within thefemur. As illustrated in FIG. 16, the implant body 1602 may include astepped shoulder 1606. In an alternate embodiment, the implant body 1602may be have a smooth shoulder.

FIGS. 17A-17F illustrate one embodiment of a system and method forinstalling a hip implant body 1702 into a femur 1700. As shown in FIG.17A, a neck sizing template 1706 may be positioned on a resected neck ofthe femur 1704. The neck sizing template 1706 may be of a size selectedto match the size of the femur 1704. For example, the femur 1704 mayhave a relatively large neck, and a correspondingly relatively largeneck sizing template 1706 may be selected for positioning on theresected neck of the femur 1704.

The neck sizing template 1706, in one embodiment, has an outer perimeter1708 similar to the outer perimeter of the implant body 1702. Forexample, the neck sizing template 1706 may have an outer perimeter 1708that is roughly equal to that of the implant body 1702. A neck sizingtemplate 1708 similar in size to the implant body 1702 provides a toolfor visualizing and testing the size of the implant body 1702 relativeto the neck of the femur 1704.

In another embodiment, the neck sizing template 1706 is undersizedrelative to the implant body 1702, having an outer perimeter 1708 lessthan the outer perimeter of the implant body 1702. A neck sizingtemplate 1708 having an outer perimeter 1708 smaller than that of theimplant body 1702 may result in an undersized channel in the femur 1704,and a tighter fit for the implant body 1702.

The neck sizing template 1706, in one embodiment, includes a firstaperture 1710 and a second aperture 1712. The first and second apertures1710, 1712 may correspond to and be alignable with a medial cannula 1714and a lateral cannula 1716 of the implant body 1702. The neck sizingtemplate 1706 may be positioned such that one of the first aperture 1710and the second aperture 1712 is positioned laterally from the center ofthe resected neck of the femur 1704 and so that the other of the firstaperture 1710 and the second aperture 1712 is positioned medially fromthe center of the resected neck of the femur 1704.

In some embodiments, a first guide wire 1718 is inserted through thefirst aperture 1710 and into the femur 1704. The neck sizing template1706 may guide and direct the first guide wire 1718 in a particulardirection and orientation as it is inserted into the femur 1704.

The first guide wire 1718 may be inserted into the femur 1704 using anytechnique. For example, the first guide wire 1718 may be driven into thefemur 1704 using a power drill. In another example, the first guide wire1718 may be impacted into the femur 1704.

Subsequent to the first guide wire 1718 being inserted into the femur1704, the neck sizing template 1706 may be removed from the femur 1704and the first guide wire 1718. With the first guide wire 1718 insertedinto the femur 1704, a cannulated tool 1720 may be positioned over thefirst guide wire 1718. The cannulated tool 1720 may be used to form afirst channel 1722 in the femur 1704 in preparation for installation ofthe implant body 1702. The cannulated tool 1720 may follow the firstguide wire 1718 and form the first channel 1722 around the first guidewire 1718. For example, the cannulated tool 1720 may be a cannulatedreamer, and the cannulated reamer may ream a channel around the firstguide wire 1718.

The neck sizing template 1708 may have a first surface 1724 and a secondsurface 1726. The first and second apertures 1710, 1712 may each runperpendicular to and through the first surface 1724 and the secondsurface 1726. In one embodiment, the first surface 1724 is substantiallyplanar or flat. The flat first surface 1724 is beneficial for stableplacement of the neck sizing template 1708 on the resected neck of thefemur 1704.

In some embodiments, the second surface 1726 has a positioning plug 1728to extend into the first channel 1722 formed around the first guide wire1718. The positioning plug 1728 may be placed over the first guide wire1718 and stabilized within the first channel 1722. The positioning plug1728 may stabilize the neck sizing template 1708 to position one of thefirst aperture 1710 and the second aperture 1712 relative to the firstguide wire 1718, with the other of the first aperture 1710 and thesecond aperture 1712 passing through the positioning plug 1728. Thefirst guide wire 1718 may be position through the positioning plug 1728via one of the first aperture 1710 and the second aperture 1712.

As shown in FIG. 17C, a second guide wire 1730 may be inserted throughthe one of the first aperture 1710 and the second aperture 1712 and intothe femur 1704. The neck sizing template 1706 may guide and direct thesecond guide wire 1730 in a particular direction and orientation as itis inserted into the femur 1704. The neck sizing template 1706 may bepositioned at least in part by one of the first guide wire 1718 and thepositioning plug 1728. The second guide wire 1730 may be substantiallyparallel to the first guide wire 1718.

The second guide wire 1730 may be inserted into the femur 1704 using anytechnique. For example, the second guide wire 1730 may be driven intothe femur 1704 using a power drill. In another example, the second guidewire 1730 may be impacted into the femur 1704.

Subsequent to the second guide wire 1730 being inserted into the femur1704, the neck sizing template 1706 may be removed from the femur 1704and the second guide wire 1730. With the second guide wire 1730 insertedinto the femur 1704, a cannulated tool 1720 may be positioned over thesecond guide wire 1730. The cannulated tool 1720 may be used to form asecond channel 1732 in the femur 1704 in preparation for installation ofthe implant body 1702. The cannulated tool 1720 may follow the secondguide wire 1730 and form the second channel 1732 around the first guidewire 1718. For example, the cannulated tool 1720 may be a cannulatedreamer, and the cannulated reamer may ream a channel around the secondguide wire 1730.

In some embodiments, the cannulated tool 1720 used to form the secondchannel 1732 has the same diameter of the cannulated tool 1720 used toform the first channel 1722. In an alternate embodiment, the secondchannel 1732 is formed using a different cannulated tool than that usedto form the first channel 1722. For example, the implant body 1702 mayhave substantially different sized medial and lateral columns, and thefirst and second channels may be formed to correspond to these sizesusing different sized cannulated tools.

In certain embodiments, the implant body 1702 may have a flare 1734along a proximal portion of the implant body 1702. An additionalcannulated tool 1736 may be used to expand a channel 1722, 1732 toaccommodate the flare 1734. For example, the flare 1734 may be at leastpartially conical, and the additional cannulated tool 1736 may be acannulated conical reamer.

As shown in FIG. 17F, the implant body 1702 may be positioned with thefirst and second guide wires 1718, 1730 running through the medial andlateral cannulas 1714, 1716, one guide wire per cannula. The implantbody 1702 may progress along the guide wires 1718, 1730 and into thefirst and second channels 1722, 1732. The implant body 1702 may bepressed into the femur 1704 using any technique for pressing an implantbody 1702 into a femur 1704. For example, the implant body 1702 may bedriven into the femur 1704 using a hammer. The guide wires 1718, 1730may guide the implant body 1702 into a desired position within the femur1704.

Those having ordinary skill in the relevant art will appreciate theadvantages provide by the features of the present disclosure. In theforegoing Detailed Description, various features of the presentdisclosure are grouped together in a single embodiment for the purposeof streamlining the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that the claimed disclosurerequires more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the followingclaims are hereby incorporated into this Detailed Description of theDisclosure by this reference, with each claim standing on its own as aseparate embodiment of the present disclosure.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the presentdisclosure. Numerous modifications and alternative arrangements may bedevised by those skilled in the art without departing from the spiritand scope of the present disclosure and the appended claims are intendedto cover such modifications and arrangements. Thus, while the presentdisclosure has been shown in the drawings and described above withparticularity and detail, it will be apparent to those of ordinary skillin the art that numerous modifications, including, but not limited to,variations in size, materials, shape, form, function and manner ofoperation, assembly and use may be made without departing from theprinciples and concepts set forth herein.

1. A method for fixating a femoral prosthesis to a proximal end of afemur comprising; providing an implant body comprising: a proximal endand a distal end, the proximal end being dimensioned and configured tosupport a prosthetic neck, the implant body comprising: a shoulder atthe proximal end, the shoulder being structured and dimensioned for atight press fit into the neck of a femur; and a trunk at the distal end,the trunk comprising: a wedge formed by a tapered portion extending inthe direction of the distal end of the implant body, and a medial columnextending from the shoulder toward the distal end, the medial columndisposed on a medial side of the wedge; a lateral column extending fromthe shoulder toward the distal end, the lateral column disposed on alateral side of the wedge; the wedge, the medial column, and the lateralcolumn to provide multi-planar stability for the implant body andsurface area apart from the shoulder for fixation of the implant bodywith the femur; inserting the implant body into an open neck of a femurso that the implant body is substantially straight along thelongitudinal axis of the femoral neck; pressing the implant body tightlyinto the femoral neck so that the shoulder wedges into the femoral neckand increases hoop stress at the femoral neck and the retentive effectof the shoulder in the neck and so that the wedge penetrates thespongiosa inside the femur to secure the implant body in the femur;positioning a neck sizing template on a resected surface of the femoralneck, the neck sizing template comprising: an outer perimeter sized tomatch an outer perimeter of the shoulder of the implant body; a firstaperture corresponding to one of a medial cannula disposed in the medialcolumn of the implant body and a lateral cannula disposed in the lateralcolumn of the implant body; and a second aperture corresponding to oneof the medial cannula the lateral cannula; installing a first guide wireinto the neck of the femur through one of the first aperture and thesecond aperture of the neck sizing template, the one of the firstaperture and the second aperture to direct the position and angle of thefirst guide wire relative to the neck of the femur; forming a firstchannel in the femur around the first guide wire, the first channelformed using a cannulated tool, the method further comprisingpositioning the first guide wire through a cannula of the cannulatedtool; installing a second guide wire into the neck of the femur throughone of the first aperture and the second aperture of the neck sizingtemplate, the one of the first aperture and the second aperture todirect the position and angle of the second guide wire relative to theneck of the femur; and forming a second channel in the femur around thesecond guide wire, the second channel formed using a cannulated tool,the method further comprising positioning the second guide wire througha cannula of the cannulated tool; wherein inserting the implant bodyinto the open neck of the femur further comprises: positioning the firstguide wire into one of the medial cannula and the lateral cannula of theimplant body; positioning the second guide wire into the other of themedial cannula and the lateral cannula of the implant body; aligning themedial column with one of the first hole and the second hole and thelateral column with the other of the first hole and the second hole; andsliding the implant body along the first and second guide wires to guidethe implant body into the femur.
 2. The method of claim 1, furthercomprising cutting the femur along a plane perpendicular to thelongitudinal axis of the femoral neck.
 3. The method of claim 1, whereinthe cannulated tool is a cannulated ream.
 4. The method of claim 1,further comprising custom shaping the implant body to a patient usingmagnetic resonance imaging (MRI) of computer tomography (CT) templating.5. The method of claim 1, further comprising custom shaping the implantbody to a patient using magnetic resonance imaging (MRI) or computertomography (CT) templating.
 6. A method for fixating a femoralprosthesis to a proximal end of the femur comprising: providing animplant body comprising: a proximal end and a distal end, the proximalend being dimensioned and configured to support a prosthetic neck, theimplant body comprising: a shoulder at the proximal end, the shoulderbeing structured and dimensioned for a tight press fit into the neck ofa femur; and a trunk at the distal end, the trunk comprising: a wedgeformed by a tapered portion extending in the direction of the distal endof the implant body, and a medial column extending from the shouldertoward the distal end, the medial column disposed on a medial side ofthe wedge; a lateral column extending from the shoulder toward thedistal end, the lateral column disposed on a lateral side of the wedge;the wedge, the medial column, and the lateral column to providemulti-planar stability for the implant body and surface area apart fromthe shoulder for fixation of the implant body with the femur; insertingthe implant body into an open neck of a femur so that the implant bodyis substantially straight along the longitudinal axis of the femoralneck; pressing the implant body tightly into the femoral neck so thatthe shoulder wedges into the femoral neck and increases hoop stress atthe femoral neck and the retentive effect of the shoulder in the neckand so that the wedge penetrates the spongiosa inside the femur tosecure the implant body in the femur; positioning a neck sizing templateon a resected surface of the femoral neck, the neck sizing templatecomprising: an outer perimeter sized to match an outer perimeter of theshoulder of the implant body; a first aperture corresponding to one of amedial cannula disposed in the medial column of the implant body and alateral cannula disposed in the lateral column of the implant body; anda second aperture corresponding to one of the medial cannula the lateralcannula; installing a first guide wire into the neck of the femurthrough one of the first aperture and the second aperture of the necksizing template, the one of the first aperture and the second apertureto direct the position and angle of the first guide wire relative to theneck of the femur; forming a first channel in the femur around the firstguide wire, the first channel formed using a cannulated tool, the methodfurther comprising positioning the first guide wire through a cannula ofthe cannulated tool; positioning the neck sizing template on theresected surface of the femoral neck such that a positioning plugdisposed on the neck sizing template extends into a first hole formed inthe femoral neck to stabilize the neck sizing template to position oneof the first aperture and the second aperture, wherein one of the firstaperture and the second aperture pass through the positioning plug.
 7. Amethod for fixating a femoral prosthesis to a proximal end of a femurcomprising: providing an implant body comprising: a proximal end and adistal end, the proximal end being dimensioned and configured to supporta prosthetic neck, the implant body comprising: a shoulder at theproximal end, the shoulder being structured and dimensioned for a tightpress fit into the neck of a femur; and a trunk at the distal end, thetrunk comprising: a wedge formed by a tapered portion extending in thedirection of the distal end of the implant body, and a medial columnextending from the shoulder toward the distal end, the medial columndisposed on a medial side of the wedge; a lateral column extending fromthe shoulder toward the distal end, the lateral column disposed on alateral side of the wedge; the wedge, the medial column, and the lateralcolumn to provide multi-planar stability for the implant body andsurface area apart from the shoulder for fixation of the implant bodywith the femur; inserting the implant body into an open neck of a femurso that the implant body is substantially straight along thelongitudinal axis of the femoral neck; pressing the implant body tightlyinto the femoral neck so that the shoulder wedges into the femoral neckand increases hoop stress at the femoral neck and the retentive effectof the shoulder in the neck and so that the wedge penetrates thespongiosa inside the femur to secure the implant body in the femur;wherein the seep of providing a stem further comprises: providing thestem in which the medial column of the trunk of said stem furthercomprises a cross-section having an outer surface that is substantiallya portion of a circle; wherein a medial column axis runs throughsuccessive center points of the medial column; wherein an outer surfaceof the medial column has a lateral cross-section comprising a medialcolumn arc having a substantially constant radius from a center point ofthe medial column; wherein a medial cannula extends along the medialcolumn axis; wherein the lateral column further comprises across-section having an outer surface that is substantially a portion ofa circle; wherein a lateral column axis extends parallel to the medialcolumn axis, the lateral column axis running through successive centerpoints of the lateral column; wherein an outer surface of the lateralcolumn has a lateral cross-section comprising a lateral column archaving a substantially constant radius from a center point of thelateral column; and wherein a lateral cannula extends along the lateralcolumn axis; and wherein a terminal flare is disposed at a proximal endof the medial column, the terminal flare configured to contact aninternal medial calcar region of the femoral bone, such that load istransferred medially from the stem component to the medial calcarregion.